Skip to content

Replace sys.stdout with sys.stdout.buffer when saving#5437

Merged
hugovk merged 5 commits into
python-pillow:masterfrom
radarhere:stdout
May 3, 2021
Merged

Replace sys.stdout with sys.stdout.buffer when saving#5437
hugovk merged 5 commits into
python-pillow:masterfrom
radarhere:stdout

Conversation

@radarhere
Copy link
Copy Markdown
Member

@radarhere radarhere commented Apr 25, 2021

Resolves #5436

https://pillow.readthedocs.io/en/stable/reference/ImageDraw.html#example-draw-a-gray-cross-over-an-image

from PIL import Image, ImageDraw

with Image.open("hopper.jpg") as im:

    draw = ImageDraw.Draw(im)
    draw.line((0, 0) + im.size, fill=128)
    draw.line((0, im.size[1], im.size[0], 0), fill=128)

    # write to stdout
    im.save(sys.stdout, "PNG")

However, running this example code gives

Traceback (most recent call last):
  File "<stdin>", line 6, in <module>
  File "PIL/Image.py", line 2172, in save
    save_handler(self, fp, filename)
  File "PIL/PngImagePlugin.py", line 1223, in _save
    fp.write(_MAGIC)
TypeError: write() argument must be str, not bytes

This PR suggests fixing this by changing im.save so that if it is passed sys.stdout (sys.stdout.mode is 'w'), then it is replaced with sys.stdout.buffer (sys.stdout.buffer.mode is 'wb').

It also changes the PSDraw() default from sys.stdout to sys.stdout.buffer, and simplifies EPS saving by abandoning the idea of wrapping fp just so that it can write strings.

@radarhere radarhere added the Bug Any unexpected behavior, until confirmed feature. label Apr 25, 2021
@radarhere radarhere mentioned this pull request Apr 25, 2021
Closed
@hugovk
Copy link
Copy Markdown
Member

hugovk commented May 3, 2021

Looks good, one question:

The docs for sys.stdout includes this:

Note: To write or read binary data from/to the standard streams, use the underlying binary buffer object. For example, to write bytes to stdout, use sys.stdout.buffer.write(b'abc').

OK, good. It continues:

However, if you are writing a library (and do not control in which context its code will be executed), be aware that the standard streams may be replaced with file-like objects like io.StringIO which do not support the buffer attribute.

Is this something we need to accomodate?

@radarhere
Copy link
Copy Markdown
Member Author

radarhere commented May 3, 2021

Nice catch. Sure, I've added a commit to allow for that.

@hugovk
Copy link
Copy Markdown
Member

hugovk commented May 3, 2021

Thank you!

@hugovk hugovk merged commit 20b8a83 into python-pillow:master May 3, 2021
@radarhere radarhere deleted the stdout branch May 3, 2021 08:58
@radarhere radarhere mentioned this pull request May 7, 2021
Merged
@infmagic2047 infmagic2047 mentioned this pull request Aug 6, 2021
Closed
@radarhere radarhere mentioned this pull request Aug 19, 2024
Merged
radarhere added a commit to radarhere/Pillow that referenced this pull request Apr 4, 2026
@radarhere
wrapper. I think this makes sense in context of python-pillow#5437 (c…
dfd5096 
…omment)
radarhere added a commit to radarhere/Pillow that referenced this pull request Apr 4, 2026
@radarhere
wrapper. I think this makes sense in context of python-pillow#5437 (c…
03261c3 
…omment)
radarhere added a commit to radarhere/Pillow that referenced this pull request Apr 30, 2026
@radarhere
wrapper. I think this makes sense in context of python-pillow#5437 (c…
d073353 
…omment)
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

No reviews

Assignees

No one assigned

Labels

Bug Any unexpected behavior, until confirmed feature.

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

Can't save PNG to sys.stdout

2 participants

@radarhere @hugovk